The invention relates to a plastic injection overmolded conductor path structure and a method for producing the plastic injection overmolded conductor path.
In the case of large numbers of pieces plastic injection overmolded conductor paths are cost-optimal electrical connection elements, for example as used in transmissions in vehicle construction. Beside the low costs their particular advantage is that they are also capable of carrying great electrical currents and can be easily constructively adjusted to the required powers and geometries. Compared to the connection technology “cable” higher tool costs are required, but the cost per piece is significantly lower.
A generic plastic injection overmolded conductor path is disclosed in DE 10 2004 020 085 A1.
Corresponding methods for producing a plastic injection overmolded conductor path are amply known from the state of the art and include, as for example disclosed in DE 10 2009 026 459 A1, the following method steps:                stamping/cutting of the conductor paths from a metal sheet, wherein connecting webs are retained at individual sites of the conductor paths in order to prevent the conductor paths from falling apart;        provision of pre-injection overmoldings: first housing sections are generated from plastic which are intended to prevent the conductor paths from falling apart as soon as the next working step is completed. For this purpose the conductor path packet with the connecting webs is inserted into a plastic injection molding tool and at the sites to be held is overmolded outside the metallic connecting webs;        removal of the connecting webs, for example by stamping, cutting, bending;        provision of a main injection overmolding: second housing sections are generated from plastic that border the first housing sections. The second housing sections provide mechanical strength to the conductor paths and insulate the conductors against each other (since they may contact each other and may cause short circuits) and against environmental influences (for example metal chippings, which may also cause short circuits).        
Because the plastic is injected under high pressure and high temperatures and the material shrinks during cooling, gaps are generated between the conductor paths and the plastic and between the plastic and the pre- and main injection overmoldings. Through these gaps air and moisture can enter. The gap between the pre- and main injection overmolding normally forms a connecting path between the conductors. When liquids enter the gap this may lead to the formation of a microfilm in the presence of corresponding environmental conditions, such as high temperatures. As a consequence the liquids may “become conductive” which may lead to short circuits. Another possibility for short circuits: reaction products may form as a result of the reaction of the liquids with components in the air, plastic components or conductor path components.